Bisazo photoconductor for electrophotography

ABSTRACT

A photoconductor for electrophotography comprises an electroconductive substrate and a photosensitive layer formed on the substrate. The photosensitive layer includes a novel bisazo compound as a charge generating substance therein. The bisazo compound is represented by the following general formula: ##STR1## wherein, A stands for a coupler residue.

This is a division of application Ser. No. 08/015,915 filed Feb. 10,1993, now abandoned which is a division of application Ser. No.07/982,897 filed Nov. 30, 1992, now U.S. Pat. No. 5,266,430 which is adivision of application Ser. No. 07/799,601 filed Nov. 27, 1991, nowU.S. Pat. No. 5,198,318, which is a division of application Ser. No.07/530,088 filed May 31, 1990, now U.S. Pat. No. 5,0087,541.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to photoconductors for electrophotography,and particularly to a photoconductor for electrophotography whichcontains a novel charge generating substance in the photosensitive layerthereof formed on an electroconductive substrate.

2. Description of the Prior Art

Photosensitive materials which have heretofore been used inphotoconductors for electrophotography include inorganic photoconductivesubstances such as selenium and selenium alloys, dispersions ofinorganic photoconductive substances such as zinc oxide and cadmiumsulfide in resin binders, organic polymeric photoconductive substancessuch as poly-N-vinylcarbazole and polyvinylanthracene, organicphotoconductive substances such as phthalocyanine compounds and bisazocompounds, dispersions of such organic photoconductive substances inresin binder, and a sputtered film of such organic photoconductivesubstances.

Photoconductors are required to have a function of maintaining a surfaceelectric charge in the dark, a function of generating an electric chargeupon receiving light, and a function of transporting an electric chargeupon receiving light. They are classified into two types ofphotoconductors, namely so-called monolayer type photoconductors, andso-called laminate type photoconductors. The former comprises a singlelayer having all of the above-mentioned three functions, and the lattercomprises functionally distinguishable laminated layers, one of whichcontributes mainly to the generation of electric charge, and another ofwhich contributes to the retention of surface electric charge in thedark and the electric charge transportation upon receiving light. In anelectrophotographic method using a photoconductor of the kind asmentioned above, for example, the Carlson's system is applied to imageformation. The image formation according to this system comprises stepsof subjecting a photoconductor in the dark to corona discharge to chargethe photoconductor, illuminating the surface of the chargedphotoconductor with imagewise light based on a manuscript or copybearing, e.g., letters and/or pictures to form a latent electrostaticimage, developing the formed latent electrostatic image with a toner,and transferring the developed toner image to a support such as a papersheet to fix the toner image on the support. After the toner imagetransfer, the photoconductor is subjected to the steps of removal of theelectric charge, removal of the remaining toner (cleaning),neutralization of the residual charge with light (erasion), and so on tobe ready for reuse.

Photoconductors for electrophotography in which use is made of organicmaterials have recently been put into practical use by virtue of theadvantageous features of flexibility, thermal stability, and/or a filmforming capacity. They include a photoconductor comprisingpoly-N-vinylcarbazole and 2,4,7-trinitrofluoren-9-on (disclosed in U.S.Pat. No. 3,484,237), a photoconductor using an organic pigment as a maincomponent (disclosed in Japanese Patent Laid-Open No. 37,543/1972), anda photoconductor using as a main component a eutectic complex composedof a dye and a resin (disclosed in Japanese Patent Laid-Open No.10,785/1972). A number of novel hydrazone compounds and bisazo compoundsand the like have also been put into practical use for photoconductors.

Although organic materials have many advantageous features mentionedabove with which inorganic materials are not endowed, however, the factis that there have been obtained no organic materials fully satisfyingall the characteristics required of a material to be used inphotoconductors for electrophotography at the present. Particularproblems involved in organic materials have been concerned withphotosensitivity and characteristics in continuous repeated use.

SUMMARY OF THE INVENTION

An object of the present invention, which has been made in view of theforegoing, is to provide a photoconductor for electrophotography for usein copying apparatuses and printers which photoconductor includes anovel organic materials not used to date as a charge generatingsubstance in the photosensitive layer, and has a high photosensitivityand excellent characteristics in repeated use.

In the first aspect of the present invention, a photoconductor forelectrophotography comprises:

an electroconductive substrate; and

a photosensitive layer formed on the substrate and including at leastone bisazo compound represented by the following general formula (I) asa charge generating substance: ##STR2## wherein A₁ is a coupler residualgroup represented by one of the following general formulae (IX) to (XI)##STR3## wherein Z is a residual group which condenses with a bezen ringto form an aromatic polycycle or heterocycle, X₁ is one of OR₁ and NR₂R₃ (each of R₁, R₂ and R₃ is selected from the group consisting of ahydrogen atom, an alkyl group, an aryl group and a heterocyclic group,which groups may be or not may be substituted), each of X₂ and X₅ isselected from the group consisting of an alkyl group, an aryl group anda heterocyclic group which groups may be or not may be substituted, eachof X₃ and X₆ is selected from the group consisting of a hydrogen atom, acyano group, a carbamoyl group, a carboxyl group, an ester group and anacyl group, each of X₄ and X₁₁ is selected from the group consisting ofa hydrogen atom, an alkyl group, a cycloalkyl group, an alkenyl group,an aralkyl group, an aryl group and a heterocyclic group, each of X₇ andX₈ is selected from the group consisting of a hydrogen atom, a halogenatom, a nitro group, an alkyl group and an alkoxy group, last two ofwhich groups may be or not may be substituted, X₉ is selected from thegroup consisting of an alkyl group, an aryl group, a carboxyl group andan ester group, X₁₀ is one of an aryl group and a heterocyclic groupwhich groups may be or not may be substituted and Y is a residual groupwhich forms an aromatic ring or a heterocycle.

Here, the photosensitive layer may comprise a layer including dispersionof a charge generating substance selected from bisazo compoundsrepresented by the general formula (I) and a charge transportingsubstance.

The photosensitive layer may comprise a laminate of a chargetransporting layer mainly composed of a charge transporting substanceand a charge generating layer including a compound selected from bisazocompounds represented by the general formula (I).

In the second aspect of the present invention, a photoconductor forelectrophotography comprises:

an electroconductive substrate; and

a photosensitive layer formed on the substrate and including at leastone bisazo compound represented by the following general formula (II) asa charge generating substance: ##STR4## wherein, A₁ is a couplerresidual group represented by one of the foregoing general formulae (IX)to (XV).

Here, the photosensitive layer may comprise a layer including dispersionof a charge generating substance selected from bisazo compoundsrepresented by the general formula (II) and a charge transportingsubstance.

The photosensitive layer may comprise a laminate of a chargetransporting layer mainly composed of a charge transporting substanceand a charge generating layer including a compound selected from bisazocompounds represented by the general formula (II).

In the third aspect of the present invention, a photoconductor forelectrophotography comprises:

an electroconductive substrate; and

a photosensitive layer formed on the substrate and including at leastone bisazo compound represented by the following general formula (III)as a charge generating substance: ##STR5## wherein each of R₄ and R₅ isselected from the group consisting of a hydrogen atom, a halogen atom,an alkyl group and an alkoxy group, which groups may be or not may besubstituted, each of R₆ and R₇ is selected from the group consisting ofa hydrogen atom, an alkyl group and an aryl group, which groups may beor not may be substituted and A₂ is a coupler residual group representedby one of the following general formulae (X) to (XVII) ##STR6## whereinZ is a residual group which condenses with a bezen ring to form anaromatic polycycle or heterocycle, X₁₄ is one of a hydrogen atom, COOR₁and CONR₂ R₃ (each of R₁, R₂ and R₃ is selected from the groupconsisting of a hydrogen atom, an alkyl group, an aryl group and aheterocyclic group, which groups may be or not may be substituted), eachof X₂ and X₅ is selected from the group consisting of an alkyl group, anaryl group and a heterocyclic group which groups may be or not may besubstituted, each of X₃ and X₆ is selected from the group consisting ofa hydrogen atom, a cyano group a carbamoyl group, a carboxyl group, anester group and an acyl group, each of X₄, X₁₁, X₁₂ and X₁₃ is selectedfrom the group consisting of a hydrogen atom, an alkyl group, acycloalkyl group, an alkenyl group, an aralkyl group, an aryl group anda heterocyclic group, each of X₇ and X₈ is selected from the groupconsisting of a hydrogen atom, a halogen atom, a nitro group, an alkylgroup and an alkoxy group, last two of which groups may be or not may besubstituted, X₉ is selected from the group consisting of an alkyl group,an aryl group, a carboxyl group and an ester group, X₁₀ is one of anaryl group and a heterocyclic group which groups may or not may besubstituted and Y is a residual group which forms an aromatic ring or aheterocycle.

Here, the photosensitive layer may comprise a layer including dispersionof a charge generating substance selected from bisazo compoundsrepresented by the general formula (III) and a charge transportingsubstance.

The photosensitive layer may comprise a laminate of a chargetransporting layer mainly composed of a charge transporting substanceand a charge generating layer including a compound selected from bisazocompounds represented by the general formula (III).

In the fourth aspect of the present invention, a photoconductor forelectrophotography comprises:

an electroconductive substrate; and

a photosensitive layer formed on the substrate and including at leastone bisazo compound represented by the following general formula (IV) asa charge generating substance: ##STR7## wherein R₈ is selected from thegroup consisting of a hydrogen atom, a halogen atom, an alkyl group, anaryl group and a cyano group and A₁ is a coupler residual represented byone of the foregoing general formulae (IX) to (XV).

Here, the photosensitive layer may comprise a layer including dispersionof a charge generating substance selected from bisazo compoundsrepresented by the general formula (IV) and a charge transportingsubstance.

The photosensitive layer may comprise a laminate of a chargetransporting layer mainly composed of a charge transporting substanceand a charge generating layer including a compound selected from bisazocompounds represented by the general formula (IV).

In the fifth aspect of the present invention, a photoconductor forelectrophotography comprises:

an electroconductive substrate; and

a photosensitive layer formed on the substrate and including at leastone bisazo compound represented by the following general formula (V) asa charge generating substance: ##STR8## wherein, A is a coupler residualgroup represented by one of the foregoing general formulae (IX) to (XV).

Here, the photosensitive layer may comprise a layer including dispersionof a charge generating substance selected from bisazo compoundsrepresented by the general formula (V) and a charge transportingsubstance.

The photosensitive layer may comprise a laminate of a chargetransporting layer mainly composed of a charge transporting substanceand a charge generating layer including a compound selected from bisazocompounds represented by the general formula (V).

In the sixth aspect of the present invention, a photoconductor forelectrophotography comprises:

an electroconductive substrate; and

a photosensitive layer formed on the substrate and including at leastone bisazo compound represented by the following general formula (VI) asa charge generating substance: ##STR9## wherein each of R₉ and R₁₀ isselected from the group consisting of a hydrogen atom, a halogen atom,an alkyl group and an aryl group and A₁ is a coupler residual grouprepresented by one of the foregoing general formulae (IX) to (XV).

Here, the photosensitive layer may comprise a layer including dispersionof a charge generating substance selected from bisazo compoundsrepresented by the general formula (VI) and a charge transportingsubstance.

The photosensitive layer may comprise a laminate of a chargetransporting layer mainly composed of a charge transporting substanceand a charge generating layer including a compound selected from bisazocompounds represented by the general formula (VI).

In the seventh aspect of the present invention, a photoconductor forelectrophotography comprises:

an electroconductive substrate; and

a photosensitive layer formed on the substrate and including at leastone bisazo compound represented by the following general formula (VII)as a charge generating substance: ##STR10## wherein, A₁ is a couplerresidual group represented by one of the foregoing general formulae (IX)to (XV).

Here, the photosensitive layer may comprise a layer including dispersionof a charge generating substance selected from bisazo compoundsrepresented by the general formula (VII) and a charge transportingsubstance.

The photosensitive layer may comprise a laminate of a chargetransporting layer mainly composed of a charge transporting substanceand a charge generating layer including a compound selected from bisazocompounds represented by the general formula (VII).

In the eighth aspect of the present invention, a photoconductor forelectrophotography comprises:

an electroconductive substrate; and

a photosensitive layer formed on the substrate and including at leastone bisazo compound represented by the following general formula (VIII)as a charge generating substance: ##STR11## wherein n is one integer of1 to 3 and A₁ is a coupler residual group represented by one of theforegoing formulae (IX) to (XV).

Here, the photosensitive layer may comprise a layer including dispersionof a charge generating substance selected from bisazo compoundsrepresented by the general formula (VIII) and a charge transportingsubstance.

The photosensitive layer may comprise a laminate of a chargetransporting layer mainly composed of a charge transporting substanceand a charge generating layer including a compound selected from bisazocompounds represented by the general formula (VIII).

The above and other objects, effects, features and advantages of thepresent invention will become more apparent from the followingdescription of embodiments thereof taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 to 3 are schematic cross-sectional views of photoconductorsaccording to the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The photoconductor of the present invention, which contains the specificbisazo compound as a charge generating substance in the photosensitivelayer thereof, may have any one of the structures as shown in FIGS. 1, 2and 3 according to the manner of application thereto of the bisazocompound. The specific bisazo compounds to be used in the presentinvention are explained later.

FIGS. 1, 2 and 3 are schematic cross-sectional views of differentembodiments of the photoconductor of the present invention,respectively.

FIG. 1 shows a cross-sectional view of a monolayer type photoconductor.A photosensitive layer 2A is provided on an electroconductivesubstrate 1. The photosensitive layer 2A comprises the above-mentionedbisazo compound as a charge generating substance 3, and a chargetransporting substance 5 both of which substances are dispersed in aresin binder matrix so that the photosensitive layer 2A functions as aphotoconductor.

FIG. 2 shows a laminate type photoconductor. A laminated photosensitivelayer 2B is provided on an electroconductive substrate 1, a lower layerof the laminate is a charge generating layer 4 including theabove-mentioned bisazo compound as a charge generating substance 3 andan upper one is a charge transporting layer 6 containing a chargetransporting substance 5 as a main component, so that the photosensitivelayer 2B functions as a photoconductor. This photoconductor is usuallyused according to the negative charge mode.

FIG. 3 shows another laminate type photoconductor having a layerstructure in reverse to that of FIG. 2. A laminated photosensitive layer2C is provided on an electroconductive substrate 1, a lower layer of thelaminate is a charge transporting layer 6 and an upper one is a chargegenerating layer 4 including the above-mentioned bisazo compound as acharge generating substance 3. The photosensitive layer also functionsas a photoconductor. This photoconductor is usually used according tothe positive charge mode. In this case, a covering layer 7 may generallybe further provided as shown in FIG. 3 to protect the charge generatinglayer 4.

Thus, two kinds of layer structure are provided for laminate typephotoconductors. The reason for this is that, even if any photoconductorwith the layer structure as shown in FIG. 2 is to be used in thepositive charge mode, no charge transporting substances adaptable to thepositive charge mode have been found yet. Accordingly, when any laminatetype photoconductor is to be used in the positive charge mode, thephotoconductor is required of a layer structure as shown in FIG. 3 forthe present.

A photoconductor as shown in FIG. 1 can be produced by dispersing acharge generating substance in a solution of a charge transportingsubstance and a resin binder and applying the resulting dispersion on anelectroconductive substrate and then drying the resulting coating film.

A photoconductor as shown in FIG. 2 can be prepared by applying anddrying a dispersion of a particulate charge generating substance in asolvent and/or a resin binder on an electroconductive substrate,followed by applying a solution of a charge transporting substance and aresin binder on the resulting layer and drying.

A photoconductor as shown in FIG. 3 can be prepared by applying anddrying a solution of a charge transporting substance and a resin binderonto an electroconductive substrate, and coating and drying dispersionof a particulate charge generating substance in a solvent and/or a resinbinder onto the resulting coating layer, followed by formation of acovering layer.

The electroconductive substrate 1 serves as an electrode of thephotoconductor and as a support for a layer or layers formed thereon.The electroconductive substrate may be in the form of a cylinder, aplate or a film, and may be made of a metallic material such asaluminum,, stainless steel or nickel, or other material having a surfacetreated to be electroconductive, such as glass so treated or a resin sotreated.

The charge generating layer 4 is formed by application of a dispersionof a bisazo compound as a charge generating substance 3 in a resinbinder, and this layer generates an electric charge upon receivinglight. It is important that the charge generating layer 4 be high notonly in charge generating efficiency but also in capability of injectingthe generated electric charge into the charge transporting layer 6 andany covering layer 7, which capability is desirably as little dependentupon the electric field as possible and high even in low intensityelectric fields. It also is possible to form a charge generating layerusing a charge generating substance as a main component in mixture witha charge transporting substance and so on. Resin binders usable in thecharge generating layer include polycarbonates, polyesters, polyamides,polyurethanes, polyvinyl chloride, epoxy resins, silicone resins,diallyl phthalate resins and homopolymers and copolymers of methacrylateesters, which may be used either alone or in appropriate combination.

The charge transporting layer 6, which is formed by application of asolution of dispersion of a hydrazone compound, a pyrazoline compound, astilbene compound, a triphenyl-amine compound, an oxazole compound or anoxadiazole compound as an organic charge transporting substance in aresin binder, exhibits a function of serving as an insulating layer inthe dark to retain an electric charge of the photoconductor as well as afunction transporting an electric charge injected from the chargegenerating layer upon receiving light. Resin binders usable in thecharge transporting layer include polycarbonates, polyesters,polyamides, polyurethanes, epoxy resins, silicone resins, andhomopolymers and copolymers of methacrylate ester.

The covering layer 7 has a function of receiving and retaining anelectric charge generated by corona discharge in the dark and acapability of transmitting light to which the charge generating layershould respond. It is necessary that the covering layer 7 transmitslight upon exposure of the photoconductor and allows the light to reachthe charge generating layer, and then undergoes the injection of anelectric charge generated in the charge generating layer to neutralizeand erases a surface electric charge. Materials usable in the coveringlayer include organic insulating film-forming materials such aspolyesters and polyamides. Such organic materials may also be used inmixture with an inorganic material such as a glass resin or SiO₂, or anelectric resistance-lowering material such as a metal or a metallicoxide. Materials usable in the covering layer are not limited to organicinsulating film-forming materials, and further include inorganicmaterials such as SiO₂, metals, and metallic oxides, which may be formedon a covering layer by an appropriate method such as vacuum evaporationand deposition, or sputtering. From the viewpoint of the aforementioneddescription, it is desirable that the material to be used in thecovering layer be as transparent as possible in the wavelength rangewherein the charge generating substance attains maximum lightabsorption.

Although the thickness of the covering layer depends on the material orcomposition thereof, it can be arbitrarily set in so far as it does notproduce any adverse effects including an increase in a residualpotential in continuous repeated use.

Now, the bisazo compounds to be used as a charge generating substance inthe present invention will be explained. The first kind of the specificbisazo compounds are represented by the following general formula (I):##STR12## wherein, A₁ is a coupler residual group represented by one ofthe following general formula (Ix) to (XV) ##STR13## wherein Z is aresidual group which condenses a bezen ring to form an aromaticpolycycle or heterocycle, X₁ is one of OR₁ and NR₂ R₃ (each of R₁, R₂and R₃ is selected from the group consisting of a hydrogen atom, analkyl group, an aryl group and a heterocyclic group, which groups may beor not may be substituted), each of X₂ and X₅ is selected from the groupconsisting of an alkyl group, an aryl group and a heterocyclic groupwhich groups may be or not may be substituted, each of X₃ and X₆ isselected from the group consisting of a hydrogen atom, a cyano group, acarbamoyl group, a carboxyl group, an ester group and an acyl group,each of X₄ and X₁₁ is selected from the group consisting of a hydrogenatom, an alkyl group, a cycloalkyl group, an alkenyl group, an aralkylgroup, an aryl group and a heterocyclic group, each of X₇ and X₈ isselected from the group consisting of a hydrogen atom, a halogen atom, anitro group, an alkyl group and an alkoxy group, last two of whichgroups may be or not may be substituted, X₉ is selected from the groupconsisting of an alkyl group, an aryl group, a carboxyl group and anester group, X₁₀ is one of an aryl group and a heterocyclic group whichgroups may be or not may be substituted and Y is a residual group whichforms an aromatic ring or a heterocycle.

The second kind of the specific bisazo compounds are represented by thefollowing general formula (II): ##STR14## wherein, A₁ is a couplerresidual group described above.

The third kind of the specific bisazo compounds are represented by thefollowing general formula (III): ##STR15## wherein, each of R₄ and R₅ isselected from the group consisting of a hydrogen atom, a halogen atom,an alkyl group and an alkoxy group, which groups may be or not may besubstituted, each of R₆ and R₇ is selected from the group consisting ofa hydrogen atom, an alkyl group and an aryl group, which groups may beor not may be substituted, A₂ is a coupler residual group represented byone of the abovedescribed general formulae (X) to (XV) and the followinggeneral formulae (XVI) to (XVII): ##STR16## wherein, Z is exactly thesame as defined relating to the general formula (IX) and each of X₁₂ andX₁₃ is selected from the group consisting of a hydrogen atom, an alkylgroup, a cycloalkyl group, an alkenyl group, an aralkyl group, an arylgroup and a heterocyclic group and X₁₄ is one of a hydrogen atom, COOR₁and COR₂ R₃.

The fourth kind of the specific bisazo compounds are represented by thefollowing general formula (IV): ##STR17## wherein R₈ is selected fromthe group consisting of a hydrogen atom, a halogen atom, an alkyl group,an aryl group and a cyano group and A₁ is an aforementioned couplerresidual group.

The fifth kind of the specific bisazo compounds are represented by thefollowing general formula (V): ##STR18## wherein, A₁ is a couplerresidual group described before.

The sixth kind of the specific bisazo compounds are represented by thefollowing general formula (VI): ##STR19## wherein each of R₉ and R₁₀ isselected from the group consisting of a hydrogen atom, a halogen atom,an alkyl group and an aryl group and A₁ is a coupler residual groupdescribed before.

The seventh kind of the specific bisazo compounds are represented by thefollowing general formula (VII): ##STR20## wherein, A₁ is a couplerresidual represented by the general formulae (IX) to (XV).

The eighth kind of the specific bisazo compounds to be used as a chargegenerating substance in the present invention are represented by thefollowing formula (VIII): ##STR21## wherein, n is an integer of 1 to 3and A₁ is a coupler residual group represented by one of the generalformulae (IX) to (XV) as described before.

Bisazo compounds, represented by the foregoing general formula (I) canbe synthesized by diazotizing an amino compound represented by thefollowing general formula (XVIII) with a conventional method andcoupling reacting obtained diazo compound with a corresponding couplerin an appropriate solvent (for example, N,N-dimethylformamide, dimethylsulfoxide and son on) under the presence of a base. ##STR22##

Specific examples of the bisazo compounds of the general formula (I)prepared in the above-mentioned manner include compounds as shown inTable A.

                  TABLE A                                                         ______________________________________                                         ##STR23##                                                                     ##STR24##                                                                    COMPOUND                                                                      No.       A1                                                                  ______________________________________                                                   ##STR25##                                                          2                                                                                        ##STR26##                                                          3                                                                                        ##STR27##                                                          4                                                                                        ##STR28##                                                          5                                                                                        ##STR29##                                                          6                                                                                        ##STR30##                                                          7                                                                                        ##STR31##                                                          8                                                                                        ##STR32##                                                          9                                                                                        ##STR33##                                                          10                                                                                       ##STR34##                                                          11                                                                                       ##STR35##                                                          12                                                                                       ##STR36##                                                          13                                                                                       ##STR37##                                                          14                                                                                       ##STR38##                                                          15                                                                                       ##STR39##                                                          16                                                                                       ##STR40##                                                          17                                                                                       ##STR41##                                                          18                                                                                       ##STR42##                                                          19                                                                                       ##STR43##                                                          20                                                                                       ##STR44##                                                          21                                                                                       ##STR45##                                                          22                                                                                       ##STR46##                                                                    or                                                                             ##STR47##                                                          ______________________________________                                    

Bisazo compounds, represented by the foregoing general formula (II) canbe synthesized by diazotizing an amino compound represented by thefollowing general formula (XIX) with a conventional method and couplingreacting obtained diazo compound with a corresponding coupler in anappropriate solvent (for example, N,N-diemthylformamide, dimethylsulfoxide and so on) under the presence of a base. ##STR48##

Specific examples of the bisazo compounds of the general formula (II)prepared in the above-mentioned manner include compounds as shown inTable B

                  TABLE B                                                         ______________________________________                                         ##STR49##                                                                     ##STR50##                                                                    COM-                                                                          POUND                                                                         No.    A1                                                                     ______________________________________                                        31                                                                                    ##STR51##                                                             32                                                                                    ##STR52##                                                             33                                                                                    ##STR53##                                                             34                                                                                    ##STR54##                                                             35                                                                                    ##STR55##                                                             36                                                                                    ##STR56##                                                             37                                                                                    ##STR57##                                                             38                                                                                    ##STR58##                                                             39                                                                                    ##STR59##                                                             40                                                                                    ##STR60##                                                             41                                                                                    ##STR61##                                                             42                                                                                    ##STR62##                                                             43                                                                                    ##STR63##                                                             44                                                                                    ##STR64##                                                             45                                                                                    ##STR65##                                                             46                                                                                    ##STR66##                                                             47                                                                                    ##STR67##                                                             48                                                                                    ##STR68##                                                             49                                                                                    ##STR69##                                                             50                                                                                    ##STR70##                                                             51                                                                                    ##STR71##                                                             52                                                                                    ##STR72##                                                                    or                                                                             ##STR73##                                                             ______________________________________                                    

Bisazo compounds, represented by the foregoing general formula (III) canbe synthesized by diazotizing an amino compound represented by thefollowing general formula (XX) with a conventional method and couplingreacting obtained diazo compound with a corresponding coupler in anappropriate solvent (for example, N,N-dimethylformamide, dimethylsulfoxide and so on) under the presence of a base. ##STR74##

Specific examples of the bisazo compounds of the general formula (III)prepared in the above-mentioned manner include compounds as shown inTable C to I.

                  TABLE C                                                         ______________________________________                                         ##STR75##                                                                    COMPOUND                                                                      No.       A2                                                                  ______________________________________                                        61                                                                                       ##STR76##                                                          62                                                                                       ##STR77##                                                          63                                                                                       ##STR78##                                                          64                                                                                       ##STR79##                                                          65                                                                                       ##STR80##                                                          66                                                                                       ##STR81##                                                          67                                                                                       ##STR82##                                                          68                                                                                       ##STR83##                                                          69                                                                                       ##STR84##                                                          70                                                                                       ##STR85##                                                          71                                                                                       ##STR86##                                                          72                                                                                       ##STR87##                                                          73                                                                                       ##STR88##                                                                    or                                                                             ##STR89##                                                          74                                                                                       ##STR90##                                                          75                                                                                       ##STR91##                                                          76                                                                                       ##STR92##                                                          77                                                                                       ##STR93##                                                          78                                                                                       ##STR94##                                                          ______________________________________                                    

                  TABLE D                                                         ______________________________________                                         ##STR95##                                                                    COM-                                                                          POUND                                                                         No.     A2                                                                    ______________________________________                                        79                                                                                     ##STR96##                                                            80                                                                                     ##STR97##                                                            81                                                                                     ##STR98##                                                            82                                                                                     ##STR99##                                                            83                                                                                     ##STR100##                                                           84                                                                                     ##STR101##                                                           85                                                                                     ##STR102##                                                           86                                                                                     ##STR103##                                                           87                                                                                     ##STR104##                                                           88                                                                                     ##STR105##                                                           ______________________________________                                    

                  TABLE E                                                         ______________________________________                                         ##STR106##                                                                   COMPOUND                                                                      No.       A2                                                                  ______________________________________                                        89                                                                                       ##STR107##                                                         90                                                                                       ##STR108##                                                         91                                                                                       ##STR109##                                                         92                                                                                       ##STR110##                                                         93                                                                                       ##STR111##                                                         94                                                                                       ##STR112##                                                         95                                                                                       ##STR113##                                                         96                                                                                       ##STR114##                                                         97                                                                                       ##STR115##                                                         98                                                                                       ##STR116##                                                         ______________________________________                                    

                  TABLE F                                                         ______________________________________                                         ##STR117##                                                                   COMPOUND                                                                      No.         A2                                                                ______________________________________                                         99                                                                                        ##STR118##                                                       100                                                                                        ##STR119##                                                       101                                                                                        ##STR120##                                                       102                                                                                        ##STR121##                                                       ______________________________________                                    

                  TABLE G                                                         ______________________________________                                         ##STR122##                                                                   COMPOUND                                                                      No.         A2                                                                ______________________________________                                        103                                                                                        ##STR123##                                                       104                                                                                        ##STR124##                                                       105                                                                                        ##STR125##                                                       106                                                                                        ##STR126##                                                       ______________________________________                                    

                  TABLE H                                                         ______________________________________                                         ##STR127##                                                                   COM-                                                                          POUND                                                                         No.    A2                                                                     ______________________________________                                        107                                                                                   ##STR128##                                                            108                                                                                   ##STR129##                                                            109                                                                                   ##STR130##                                                            110                                                                                   ##STR131##                                                            ______________________________________                                    

                  TABLE I                                                         ______________________________________                                         ##STR132##                                                                   COM-                                                                          POUND                                                                         No.    A2                                                                     ______________________________________                                        111                                                                                   ##STR133##                                                            112                                                                                   ##STR134##                                                            113                                                                                   ##STR135##                                                            114                                                                                   ##STR136##                                                            ______________________________________                                    

Bisazo compounds, represented by the foregoing general formula (IV) canbe synthesized by diazotizing an amino compound represented by thefollowing general formula (XXI) with a conventional method and couplingreacting obtained diazo compound with a corresponding coupler in anappropriate solvent (for example, N,N-dimethylformamide, dimethylsulfoxide and so on) under the presence of a base. ##STR137##

Specific examples of the bisazo compounds of the general formula (IV)prepared in the above-mentioned manner include compounds as shown inTables J to K.

                  TABLE J                                                         ______________________________________                                         ##STR138##                                                                   COMPOUND                                                                      No.       A1                                                                  ______________________________________                                        121                                                                                      ##STR139##                                                         122                                                                                      ##STR140##                                                         123                                                                                      ##STR141##                                                         124                                                                                      ##STR142##                                                         125                                                                                      ##STR143##                                                         126                                                                                      ##STR144##                                                         127                                                                                      ##STR145##                                                         128                                                                                      ##STR146##                                                         129                                                                                      ##STR147##                                                         130                                                                                      ##STR148##                                                         131                                                                                      ##STR149##                                                         132                                                                                      ##STR150##                                                         133                                                                                      ##STR151##                                                         134                                                                                      ##STR152##                                                         135                                                                                      ##STR153##                                                         136                                                                                      ##STR154##                                                         137                                                                                      ##STR155##                                                         138                                                                                      ##STR156##                                                         139                                                                                      ##STR157##                                                         140                                                                                      ##STR158##                                                         141                                                                                      ##STR159##                                                         142                                                                                      ##STR160##                                                                   or                                                                             ##STR161##                                                         ______________________________________                                    

                                      TABLE K                                     __________________________________________________________________________     ##STR162##                                                                   COMPOUND                                                                      No.       R.sub.11                                                                            A1                                                            __________________________________________________________________________    143       CH.sub.3                                                                             ##STR163##                                                   144       CH.sub.3                                                                             ##STR164##                                                   145                                                                                      ##STR165##                                                                          ##STR166##                                                   146       CH.sub.3                                                                             ##STR167##                                                   147                                                                                      ##STR168##                                                                          ##STR169##                                                   148       CN                                                                                   ##STR170##                                                   149       CH.sub.3                                                                             ##STR171##                                                   150       C.sub.2 H.sub.5                                                                      ##STR172##                                                   151       CH.sub.3                                                                             ##STR173##                                                   152       Cl                                                                                   ##STR174##                                                   153                                                                                      ##STR175##                                                                          ##STR176##                                                   154       CH.sub.3                                                                             ##STR177##                                                   155       CH.sub.3                                                                             ##STR178##                                                   156       C.sub.2 H.sub.5                                                                      ##STR179##                                                   157       CN                                                                                   ##STR180##                                                   158       CH.sub.3                                                                             ##STR181##                                                   159       C.sub.2 H.sub.5                                                                      ##STR182##                                                   160                                                                                      ##STR183##                                                                          ##STR184##                                                   161       CH.sub.3                                                                             ##STR185##                                                   162       Cl                                                                                   ##STR186##                                                   163       C.sub.2 H.sub.5                                                                      ##STR187##                                                   164       CN                                                                                   ##STR188##                                                   165       CH.sub.3                                                                             ##STR189##                                                   __________________________________________________________________________

Bisazo compounds, represented by the foregoing general formula (V) canbe synthesized by diazotizing an amino compound represented by thefollowing general formula (XXII) with a conventional method and couplingreacting obtained diazo compound with a corresponding coupler in anappropriate solvent (for example, N,N-dimethylformamide, dimethylsulfoxide and so on) under the presence of a base. ##STR190##

Specific examples of the bisazo compounds of the general formula (V)prepared in the above-mentioned manner include compounds as shown inTables L and M.

                  TABLE L                                                         ______________________________________                                         ##STR191##                                                                    ##STR192##                                                                   COM-                                                                          POUND                                                                         No.    A1                                                                     ______________________________________                                        171                                                                                   ##STR193##                                                            172                                                                                   ##STR194##                                                            173                                                                                   ##STR195##                                                            174                                                                                   ##STR196##                                                            175                                                                                   ##STR197##                                                            176                                                                                   ##STR198##                                                            177                                                                                   ##STR199##                                                            178                                                                                   ##STR200##                                                            179                                                                                   ##STR201##                                                            180                                                                                   ##STR202##                                                            181                                                                                   ##STR203##                                                            182                                                                                   ##STR204##                                                            183                                                                                   ##STR205##                                                            184                                                                                   ##STR206##                                                            185                                                                                   ##STR207##                                                            186                                                                                   ##STR208##                                                            187                                                                                   ##STR209##                                                            188                                                                                   ##STR210##                                                            189                                                                                   ##STR211##                                                            190                                                                                   ##STR212##                                                            191                                                                                   ##STR213##                                                            192                                                                                   ##STR214##                                                            ______________________________________                                    

                  TABLE M                                                         ______________________________________                                         ##STR215##                                                                    ##STR216##                                                                   COM-                                                                          POUND                                                                         No.    A1                                                                     ______________________________________                                        193                                                                                   ##STR217##                                                            194                                                                                   ##STR218##                                                            195                                                                                   ##STR219##                                                            196                                                                                   ##STR220##                                                            197                                                                                   ##STR221##                                                            198                                                                                   ##STR222##                                                            199                                                                                   ##STR223##                                                            200                                                                                   ##STR224##                                                            201                                                                                   ##STR225##                                                            202                                                                                   ##STR226##                                                            203                                                                                   ##STR227##                                                            204                                                                                   ##STR228##                                                            205                                                                                   ##STR229##                                                            206                                                                                   ##STR230##                                                            207                                                                                   ##STR231##                                                            208                                                                                   ##STR232##                                                            209                                                                                   ##STR233##                                                            210                                                                                   ##STR234##                                                            211                                                                                   ##STR235##                                                            212                                                                                   ##STR236##                                                            213                                                                                   ##STR237##                                                            214                                                                                   ##STR238##                                                            ______________________________________                                    

Bisazo compounds, represented by the foregoing general formula (VI) canbe synthesized by diazotizing an amino compound represented by thefollowing general formula (XXIII) with a conventional method andcoupling reacting obtained diazo compound with a corresponding couplerin an appropriate solvent (for example, N,N-dimethylformamide, dimethylsulfoxide and so on) under the presence of a base. ##STR239##

Specific examples of the bisazo compounds of the general formula (VI)prepared in the above-mentioned manner include compounds as shown inTables N and P.

                  TABLE N                                                         ______________________________________                                         ##STR240##                                                                   COM-                                                                          POUND                                                                         No.     A1                                                                    ______________________________________                                        221                                                                                    ##STR241##                                                           222                                                                                    ##STR242##                                                           223                                                                                    ##STR243##                                                           224                                                                                    ##STR244##                                                           225                                                                                    ##STR245##                                                           226                                                                                    ##STR246##                                                           227                                                                                    ##STR247##                                                           228                                                                                    ##STR248##                                                           229                                                                                    ##STR249##                                                           230                                                                                    ##STR250##                                                           231                                                                                    ##STR251##                                                           232                                                                                    ##STR252##                                                           233                                                                                    ##STR253##                                                           234                                                                                    ##STR254##                                                           235                                                                                    ##STR255##                                                           236                                                                                    ##STR256##                                                           237                                                                                    ##STR257##                                                           238                                                                                    ##STR258##                                                           239                                                                                    ##STR259##                                                           240                                                                                    ##STR260##                                                           241                                                                                    ##STR261##                                                           242                                                                                    ##STR262##                                                           ______________________________________                                    

                  TABLE P                                                         ______________________________________                                         ##STR263##                                                                   COM-                                                                          POUND                                                                         No.    A1                                                                     ______________________________________                                        243                                                                                   ##STR264##                                                            244                                                                                   ##STR265##                                                            245                                                                                   ##STR266##                                                            246                                                                                   ##STR267##                                                            247                                                                                   ##STR268##                                                            248                                                                                   ##STR269##                                                            249                                                                                   ##STR270##                                                            250                                                                                   ##STR271##                                                            251                                                                                   ##STR272##                                                            252                                                                                   ##STR273##                                                            253                                                                                   ##STR274##                                                            254                                                                                   ##STR275##                                                            255                                                                                   ##STR276##                                                            256                                                                                   ##STR277##                                                            257                                                                                   ##STR278##                                                            258                                                                                   ##STR279##                                                            259                                                                                   ##STR280##                                                            260                                                                                   ##STR281##                                                            261                                                                                   ##STR282##                                                            262                                                                                   ##STR283##                                                            263                                                                                   ##STR284##                                                            264                                                                                   ##STR285##                                                            ______________________________________                                    

Bisazo compounds, represented by the foregoing general formula (VII) canbe synthesized by diazotizing an amino compound represented by thefollowing general formula (XXIV) with a conventional method and couplingreacting obtained diazo compound with a corresponding coupler in anappropriate solvent (for example, N,N-dimethylformamide, dimethylsulfoxide and so on) under the presence of a base. ##STR286##

Specific examples of the bisazo compounds of the general formula (VII)prepared in the above-mentioned manner include compounds as shown inTables Q and R.

                  TABLE Q                                                         ______________________________________                                         ##STR287##                                                                    ##STR288##                                                                   COMPOUND                                                                      No.       A1                                                                  ______________________________________                                        271                                                                                      ##STR289##                                                         272                                                                                      ##STR290##                                                         273                                                                                      ##STR291##                                                         274                                                                                      ##STR292##                                                         275                                                                                      ##STR293##                                                         276                                                                                      ##STR294##                                                         277                                                                                      ##STR295##                                                         278                                                                                      ##STR296##                                                         279                                                                                      ##STR297##                                                         280                                                                                      ##STR298##                                                         281                                                                                      ##STR299##                                                         282                                                                                      ##STR300##                                                         283                                                                                      ##STR301##                                                         284                                                                                      ##STR302##                                                         285                                                                                      ##STR303##                                                         286                                                                                      ##STR304##                                                         287                                                                                      ##STR305##                                                         288                                                                                      ##STR306##                                                         289                                                                                      ##STR307##                                                         290                                                                                      ##STR308##                                                         291                                                                                      ##STR309##                                                         292                                                                                      ##STR310##                                                                   or                                                                             ##STR311##                                                         ______________________________________                                    

                  TABLE R                                                         ______________________________________                                         ##STR312##                                                                    ##STR313##                                                                   COM-                                                                          POUND                                                                         No.    A1                                                                     ______________________________________                                        293                                                                                   ##STR314##                                                            294                                                                                   ##STR315##                                                            295                                                                                   ##STR316##                                                            296                                                                                   ##STR317##                                                            297                                                                                   ##STR318##                                                            298                                                                                   ##STR319##                                                            299                                                                                   ##STR320##                                                            300                                                                                   ##STR321##                                                            301                                                                                   ##STR322##                                                            302                                                                                   ##STR323##                                                            303                                                                                   ##STR324##                                                            304                                                                                   ##STR325##                                                            305                                                                                   ##STR326##                                                            306                                                                                   ##STR327##                                                            307                                                                                   ##STR328##                                                            308                                                                                   ##STR329##                                                            309                                                                                   ##STR330##                                                            310                                                                                   ##STR331##                                                            311                                                                                   ##STR332##                                                            312                                                                                   ##STR333##                                                            313                                                                                   ##STR334##                                                            314                                                                                   ##STR335##                                                                   or                                                                             ##STR336##                                                            ______________________________________                                    

Bisazo compounds, represented by the foregoing general formula (VIII)can be synthesized by diazotizing an amino compound represented by thefollowing general formula (XXV) with a conventional method and couplingreacting obtained diazo compound with a corresponding coupler in anappropriate solvent (for example, N,N-dimethylformamide, dimethylsulfoxide and so on) under the presence of a base. ##STR337##

Specific examples of the bisazo compounds of the general formula (VIII)prepared in the above-mentioned manner include compounds as shown inTables S to U.

                  TABLE S                                                         ______________________________________                                         ##STR338##                                                                    ##STR339##                                                                   COM-                                                                          POUND                                                                         No.    A1                                                                     ______________________________________                                        321                                                                                   ##STR340##                                                            322                                                                                   ##STR341##                                                            323                                                                                   ##STR342##                                                            324                                                                                   ##STR343##                                                            325                                                                                   ##STR344##                                                            326                                                                                   ##STR345##                                                            327                                                                                   ##STR346##                                                            328                                                                                   ##STR347##                                                            329                                                                                   ##STR348##                                                            330                                                                                   ##STR349##                                                            331                                                                                   ##STR350##                                                            332                                                                                   ##STR351##                                                            333                                                                                   ##STR352##                                                            334                                                                                   ##STR353##                                                            335                                                                                   ##STR354##                                                            336                                                                                   ##STR355##                                                            337                                                                                   ##STR356##                                                            338                                                                                   ##STR357##                                                            339                                                                                   ##STR358##                                                            340                                                                                   ##STR359##                                                            341                                                                                   ##STR360##                                                            342                                                                                   ##STR361##                                                                   or                                                                             ##STR362##                                                            ______________________________________                                    

                  TABLE T                                                         ______________________________________                                         ##STR363##                                                                    ##STR364##                                                                   COMPOUND                                                                      No.       A1                                                                  ______________________________________                                        343                                                                                      ##STR365##                                                         344                                                                                      ##STR366##                                                         345                                                                                      ##STR367##                                                         346                                                                                      ##STR368##                                                         347                                                                                      ##STR369##                                                         348                                                                                      ##STR370##                                                         349                                                                                      ##STR371##                                                         350                                                                                      ##STR372##                                                         351                                                                                      ##STR373##                                                         352                                                                                      ##STR374##                                                         353                                                                                      ##STR375##                                                         354                                                                                      ##STR376##                                                         355                                                                                      ##STR377##                                                         356                                                                                      ##STR378##                                                         357                                                                                      ##STR379##                                                         358                                                                                      ##STR380##                                                         359                                                                                      ##STR381##                                                         360                                                                                      ##STR382##                                                         361                                                                                      ##STR383##                                                         362                                                                                      ##STR384##                                                         363                                                                                      ##STR385##                                                         364                                                                                      ##STR386##                                                                   or                                                                             ##STR387##                                                         ______________________________________                                    

                  TABLE U                                                         ______________________________________                                         ##STR388##                                                                    ##STR389##                                                                   COMPOUND                                                                      No.       A1                                                                  ______________________________________                                        365                                                                                      ##STR390##                                                         366                                                                                      ##STR391##                                                         367                                                                                      ##STR392##                                                         368                                                                                      ##STR393##                                                         369                                                                                      ##STR394##                                                         370                                                                                      ##STR395##                                                         371                                                                                      ##STR396##                                                         372                                                                                      ##STR397##                                                         373                                                                                      ##STR398##                                                         374                                                                                      ##STR399##                                                         375                                                                                      ##STR400##                                                         376                                                                                      ##STR401##                                                         377                                                                                      ##STR402##                                                         378                                                                                      ##STR403##                                                         379                                                                                      ##STR404##                                                         380                                                                                      ##STR405##                                                         381                                                                                      ##STR406##                                                         382                                                                                      ##STR407##                                                         383                                                                                      ##STR408##                                                         384                                                                                      ##STR409##                                                         385                                                                                      ##STR410##                                                         386                                                                                      ##STR411##                                                                   or                                                                             ##STR412##                                                         ______________________________________                                    

As for the use of the bisazo compounds represented by the generalformulae given above in photosensitive layers, there has been noprecedent before. In the course of the intensive study of variousorganic materials as made in an attempt to achieve the above object, thepresent inventors conducted a number of experiments with those bisazocompounds and, as a result, found that the use of such specific bisazocompounds represented by the above general formulae (I) to (VIII) ascharge generating substances is very effective in improvingelectrophotographic characteristics. Based on this finding,photoconductors having high sensitivity and good repeated usecharacteristics are obtained.

Examples will now be given, wherein various compounds represented by thegeneral formulae (I) to (VIII) were respectively used to producephotoconductors.

EXAMPLE 1

50 parts by weight of the bisazo compound No. 1, 100 parts by weight ofa polyester resin (Vylon 200, manufactured by Toyobo Co., Ltd.) and 100parts by weight of1-phenyl-3-(p-diethylaminaostyryl)-5-(p-diethylaminophenyl)-2-pyrazoline(ASPP) are kneaded with tetrahydrofuran (THF) as a solvent with a mixerfor 3 hours to prepare a coating liquid. The coating liquid was appliedonto an aluminum-deposited polyester film (AT-PET) as anelectroconductive substrate by means of the wire bar technique to form aphotosensitive layer having a dry thickness of 15 μm. Thus, aphotoconductor with the structure shown in FIG. 1 was produced.

EXAMPLE 2

First, 100 parts by weight ofp-diethylaminobenzaldehyde-diphenylhydrazone (ABPH) and 100 parts byweight of polycarbonate resin (Panlite L-1250 manufactured by Teijinchemicals Co., Ltd.) were solved in methylene chloride to prepare acoating liquid. The coating liquid was applied onto analuminum-deposited polyester film substrate by the wire bar technique toform a charge transporting layer having a dry thickness of 15 μm. 50parts by weight of the compound No. 2 and 50 parts by weight of apolyester resin (Vylon 200) were kneaded with a mixer for 3 hourstogether with THF as a solvent to prepare a coating liquid, which wasthen applied onto the charge transporting layer by the wire bartechnique to form a charge generating layer having a dry thickness of0.5 μm. Thus, a photoconductor with a structure corresponding to thatshown in FIG. 3 was produced. The covering layer, which is not directlyrelated to the present invention was not provided.

EXAMPLE 3

A charge transporting layer was formed in substantially the same manneras in Example 2 except that (α-phenyl-4'-N,N-dimethylaminostilbene,which is a stilbene compound, was used to replace ABPH as a chargetransporting substance. Then a charge generating layer was formed on thecharge transporting layer in the same manner as in Example 2, thus aphotoconductor was produced.

EXAMPLE 4

A charge transporting layer was formed in substantially the same manneras in Example 2 except that tri(p-tolyl)amine, which is a triphenylaminecompound, was used to replace ABPH as a charge transporting substance.Then a charge generating layer was formed on the charge transportinglayer in the same manner as in Example 2, thus a photoconductor wasproduced.

EXAMPLE 5

A charge transporting layer was formed in substantially the same manneras in Example 2 except that2,5-bis(p-diethylaminophenyl)-1,3,4-oxadiazole, which is an oxadiazolecompound, was used to replace ABPH as a charge transporting substance.Then a charge generating layer was formed on the charge transportinglayer in the same manner as in Example 2, thus a photoconductor wasproduced.

The electrophotographic characteristics of the photoconductors thusproduced were measured by utilizing an electrostatic recording papertesting apparatus (Kawaguchi Denki Model SP-428). The result obtainedare shown in Table 1.

The surface potential V_(s) (volts) of each photoconductor is an initialsurface potential which was measured when the surface of thephotoconductor was positively charged in the dark by corona discharge at+6.0 KV for 10 seconds. After the discontinuation of the coronadischarge, the photoconductor was allowed to stand in the dark for 2seconds, after which the surface potential V_(d) (volts) of thephotoconductor was measured. Subsequently, the surface of thephotoconductor was irradiated with white light at an illuminance of 2luxes and the time (seconds) required for the irradiation to decreasethe surface potential of the photoconductor to half of the V_(d) wasmeasured, than from which the half decay exposure amount E_(1/2)(lux·sec) was calculated. Also, the surface potential of thephotoconductor after 10 seconds of irradiation thereof with white lightat an illuminance of 2 luxes was measured as a residual potential V_(r)(volts).

                  TABLE 1                                                         ______________________________________                                                 V.sub.s   V.sub.r E.sub.1/2                                                   (volt)    (volt)  (lux · sec)                               ______________________________________                                        Example 1  600         50      4.3                                            Example 2  620         40      5.0                                            Example 3  620         40      5.2                                            Example 4  650         80      4.1                                            Example 5  600         60      4.3                                            ______________________________________                                    

As can be seen in Table 1, the photoconductors of Examples 1 to 5 havegood characteristics in the half decay exposure amounts E_(1/2) and theresidual potentials V_(r).

EXAMPLE 6

100 parts by weight of each of respective bisazo compounds Nos. from 3to 22 and 100 parts by weight of polyester resin (Vylon 200) werekneaded with THF as a solvent with a mixer for 3 hours to prepare acoating liquid. The respective coating liquids were applied ontoaluminum substrates to form a charge generating layer having a drythickness of about 0.5 μm. Further, the coating liquid of ABPH preparedin substantially the same manner as in Example 2 was applied on therespective charge generating layer having a thickness of about 15 μm,thus photoconductors were produced.

The electrophotographic characteristics of the photoconductors thusproduced were measured by utilizing an electrostatic recording papertesting apparatus SP-428. The results of the measurements are shown inTable 2.

The surface potential Vs (volts) of each photoconductor is an initialsurface potential which was measured when the surface of thephotoconductor was positively charged in the dark by corona discharge at-6.0 kV for 10 seconds. After the discontinuation of the coronadischarge, the photoconductor was allowed to stand in the dark for 2seconds, after which the surface potential V_(d) (volts) of thephotoconductor was measured. Subsequently, the surface of thephotoconductor was irradiated with white light at an illuminance of 2luxes and the time (seconds) required for the irradiation to decreasethe surface potential of the photoconductor to half of the V_(d) wasmeasured, then from which the half decay exposure amount E_(1/2)(lux·sec) was calculated.

As can be seen in Table 2, the photoconductors using the bisazo compoundNos. 3 to 22 as a charge generating substance have good characteristicsin the half decay exposure amount E_(1/2).

                  TABLE 2                                                         ______________________________________                                        Compound      E.sub.1/2                                                       No.           (lux · sec)                                            ______________________________________                                         3            3.9                                                              4            6.0                                                              5            4.4                                                              6            6.0                                                              7            7.2                                                              8            6.8                                                              9            5.5                                                             10            4.4                                                             11            5.1                                                             12            6.3                                                             13            4.3                                                             14            5.9                                                             15            5.8                                                             16            4.6                                                             17            5.2                                                             18            5.8                                                             19            5.4                                                             20            7.6                                                             21            6.1                                                             22            4.9                                                             ______________________________________                                    

EXAMPLE 7

A photoconductor was produced in the same manner as in Example 1 exceptthat compound No. 31 was used to replace compound No. 1 as a chargegenerating substance.

EXAMPLE 8

A photoconductor was produced in the same manner as in Example 2 exceptthat compound No. 32 was used to replace compound No. 2 as a chargegenerating. substance.

EXAMPLE 9

A charge transporting layer was formed in substantially the same manneras in Example 8 except that α-phenyl-4'-N,N-dimethylaminostilbene wasused to replace ABPH as a charge transporting substance. Then a chargegenerating layer was formed on the charge transporting layer in the samemanner as in Example 8, thus a photoconductor was produced.

EXAMPLE 10

A charge transporting layer was formed in substantially the same manneras in Example 8 except that tri(p-tolyl)amine was used to replace ABPHas a charge transporting substance. Then a charge generating layer wasformed on the charge transporting layer in the same manner as in Example8, thus a photoconductor was produced.

EXAMPLE 11

A charge transporting layer was formed in substantially the same manneras in Example 8 except that2,5-bis(p-diethylaminophenyl)-1,3,4-oxadiazole was used to replace ABPHas a charge transporting substance. Then a charge generating layer wasformed on the charge transporting layer in the same manner as in Example8, thus a photoconductor was produced.

The electrophotographic characteristics of the photoconductors thusproduced were measured in the same manner as in Examples 1 to 5 byutilizing an electrostatic recording paper testing apparatus ModelSP-428. The result obtained are shown in Table 3.

                  TABLE 3                                                         ______________________________________                                                 V.sub.s   V.sub.r E.sub.1/2                                                   (volt)    (volt)  (lux · sec)                               ______________________________________                                        Example 7  600         50      4.3                                            Example 8  620         40      5.0                                            Example 9  620         40      5.2                                            Example 10 650         80      4.1                                            Example 11 600         60      4.3                                            ______________________________________                                    

As can be seen in Table 3, the photoconductors of Examples 7 to 11 havegood characteristics in the half decay exposure and the residual amountsE_(1/2) potentials V_(r).

EXAMPLE 12

100 parts by weight of each of respective bisazo compounds Nos. from 33to 52 and 100 parts by weight of polyester resin (Vylon 200) werekneaded with THF as a solvent with a mixer for 3 hours to prepare acoating liquid. The respective coating liquids were applied ontoaluminum substrates to form a charge generating layer having a drythickness of about 0.5 μm. Further, the coating liquid of ABPH preparedin substantially the same manner as in Example 8 was applied on therespective charge generating layer having a thickness of about 15 μm,thus photoconductors were produced.

The electrophotographic characteristics of the photoconductors thusproduced were measured by utilizing an electrostatic recording papertesting apparatus SP-428 and in the same manner as in Example 6. Theresults of the measurements are shown in Table 4.

As can be seen in Table 4, the photoconductors using the bisazo compoundNos. 33 to 52 as a charge generating substance have good characteristicsin the half decay exposure amount E_(1/2).

                  TABLE 4                                                         ______________________________________                                        Compound      E.sub.1/2                                                       No.           (lux · sec)                                            ______________________________________                                        33            3.9                                                             34            6.0                                                             35            4.4                                                             36            6.0                                                             37            7.2                                                             38            6.8                                                             39            5.5                                                             40            4.4                                                             41            5.1                                                             42            6.3                                                             43            4.3                                                             44            5.9                                                             45            5.8                                                             46            4.6                                                             47            5.2                                                             48            5.8                                                             49            5.4                                                             50            7.6                                                             51            6.1                                                             52            4.9                                                             ______________________________________                                    

EXAMPLE 13

A photoconductor was produced in the same manner as in Example 1 exceptthat compound No. 61 was used to replace compound No. 1 as a chargegenerating substance.

EXAMPLE 14

A photoconductor was produced in the same manner as in Example 2 exceptthat compound No. 62 was used to replace compound No. 2 as a chargegenerating substance.

EXAMPLE 15

A charge transporting layer was formed in substantially the same manneras in Example 14 except that α-phenyl-4'-N,N-dimethylaminostilbene wasused to replace ABPH as a charge transporting substance. Then a chargegenerating layer was formed on the charge transporting layer in the samemanner as-in Example 14, thus a photoconductor was produced.

EXAMPLE 16

A charge transporting layer was formed in substantially the same manneras in Example 14 except that tri(p-tolyl)amine was used to replace ABPHas a charge transporting substance. Then a charge generating layer wasformed on the charge transporting layer in the same manner as in Example14, thus a photoconductor was produced.

EXAMPLE 17

A charge transporting layer was formed in substantially the same manneras in Example 14 except that2,5-bis(p-diethylaminophenyl)-1,3,4-oxadiazole was used to replace ABPHas a charge transporting substance. Then a charge generating layer wasformed on the charge transporting layer in the same manner as in Example14, thus a photoconductor was produced.

The electrophotographic characteristics of the photoconductors thusproduced were measured by utilizing an electrostatic recording papertesting apparatus Model SP-428 and in the same manner as in Examples 1to 5. The result obtained are shown in Table 5.

                  TABLE 5                                                         ______________________________________                                                 V.sub.s   V.sub.r E.sub.1/2                                                   (volt)    (volt)  (lux · sec)                               ______________________________________                                        Example 13 600         80      6.0                                            Example 14 650         60      4.2                                            Example 15 630         90      5.3                                            Example 16 700         100     5.9                                            Example 17 620         70      4.8                                            ______________________________________                                    

As can be seen in Table 5, the photoconductors of Examples 13 to 17 havegood characteristics in the half decay exposure amounts E_(1/2) and theresidual potentials V_(r).

EXAMPLE 18

100 parts by weight of each of respective bisazo compounds Nos. from 63to 114 and 100 parts by weight of polyester resin (Vylon 200) werekneaded with THF as a solvent with a mixer for 3 hours to prepare acoating liquid. The respective coating liquids were applied ontoaluminum substrates to form a charge generating layer having a drythickness of about 0.5 μm. Further, the coating liquid of ABPH preparedin substantially the same manner as in Example 14 was applied on therespective charge generating layer having a thickness of about 15 μm,thus photoconductors were produced.

The electrophotographic characteristics of the photoconductors thusproduced were measured by utilizing an electrostatic recording papertesting apparatus SP-428 and in the same manner as in the Example 6. Theresults of the measurements are-shown in Table 6.

As can be seen in Table 6, the photoconductors using the bisazo compoundNos. 63 to 114 as a charge generating substance have goodcharacteristics in the half decay exposure amount E_(1/2).

                  TABLE 6                                                         ______________________________________                                        Compound  E.sub.1/2                                                           No.       (lux · sec)                                                ______________________________________                                        63        5.8                                                                 64        4.2                                                                 65        6.9                                                                 66        3.4                                                                 67        4.9                                                                 68        5.3                                                                 69        6.6                                                                 70        6.1                                                                 71        5.8                                                                 72        4.3                                                                 73        3.9                                                                 74        4.7                                                                 75        6.1                                                                 76        5.4                                                                 77        5.7                                                                 78        5.0                                                                 79        3.8                                                                 80        5.6                                                                 81        6.3                                                                 82        4.2                                                                 83        4.9                                                                 84        6.5                                                                 85        5.7                                                                 86        5.3                                                                 87        6.1                                                                 88        4.9                                                                 89        5.5                                                                 90        4.8                                                                 91        4.3                                                                 92        5.6                                                                 93        6.8                                                                 94        6.1                                                                 95        6.0                                                                 96        3.9                                                                 97        4.8                                                                 98        5.2                                                                 99        5.9                                                                 100       4.4                                                                 101       6.9                                                                 102       6.3                                                                 103       5.4                                                                 104       6.2                                                                 105       3.1                                                                 106       6.5                                                                 107       7.3                                                                 108       4.2                                                                 109       6.4                                                                 110       5.1                                                                 111       6.7                                                                 112       3.8                                                                 113       4.6                                                                 114       5.2                                                                 ______________________________________                                    

EXAMPLE 19

A photoconductor was produced in the same manner as in Example 1 exceptthat compound No. 121 was used to replace compound No. 1 as a chargegenerating substance.

EXAMPLE 20

A photoconductor was produced in the same manner as in Example 2 exceptthat compound No. 122 was used to replace compound No. 2 as a chargegenerating substance.

EXAMPLE 21

A charge transporting layer was formed in substantially the same manneras in Example 20 except that α-phenyl-4'-N,N-dimethylaminostilbene wasused to replace ABPH as a charge transporting substance. Then a chargegenerating layer was formed on the charge transporting layer in the samemanner as in Example 20, thus a photoconductor was produced.

EXAMPLE 22

A charge transporting layer was formed in substantially the same manneras in Example 20 except that tri(p-tolyl)amine was used to replace ABPHas a charge transporting substance. Then a charge generating layer wasformed on the charge transporting layer in the same manner as in Example20, thus a photoconductor was produced.

EXAMPLE 23

A charge transporting layer was formed in substantially the same manneras in Example 20 except that2,5-bis(p-diethylaminophenyl)-1,3,4-oxadiazole was used to replace ABPHas a charge transporting substance. Then a charge generating layer wasformed on the charge transporting layer in the same manner as in Example20, thus a photoconductor was produced.

The electrophotographic characteristics of the photoconductors thusproduced were measured in the same manner as in Examples 1 to 5 byutilizing an electrostatic recording paper testing apparatus ModelSP-428. The result obtained are shown in Table 7.

                  TABLE 7                                                         ______________________________________                                                 V.sub.s   V.sub.r E.sub.1/2                                                   (volt)    (volt)  (lux · sec)                               ______________________________________                                        Example 19 710         50      4.1                                            Example 20 620         60      5.3                                            Example 21 710         30      3.8                                            Example 22 660         50      4.7                                            Example 23 660         50      5.1                                            ______________________________________                                    

As can be seen in Table 7, the photoconductors of Examples 19 to 23 havegood characteristics in the half decay exposure amounts E_(1/2) and theresidual potentials V_(r).

EXAMPLE 24

100 parts by weight of each of respective bisazo compounds Nos. from 123to 165 and 100 parts by weight of polyester resin (Vylon 200) werekneaded with THF as a solvent with a mixer for 3 hours to prepare acoating liquid. The respective coating liquids were applied ontoaluminum substrates to form a charge generating layer having a drythickness of about 0.5 μm. Further, the coating liquid of ABPH preparedin substantially the same manner as in Example 2 was applied on therespective charge generating layer having a thickness of about 15 μm,thus photoconductors were produced.

The electrophotographic characteristics of the photoconductors thusproduced were measured in the same manner a3 in Example 6 by utilizingan electrostatic recording paper testing apparatus SP-428. The resultsof the measurements are shown in Table 8.

As can be seen in Table 8, the photoconductors using the bisazo compoundNos. 123 to 165 as a charge generating substance have goodcharacteristics in the half decay exposure amount E_(1/2).

                  TABLE 8                                                         ______________________________________                                        Compound      E.sub.1/2                                                       No.           (lux · sec)                                            ______________________________________                                        123           4.7                                                             124           4.6                                                             125           4.5                                                             126           5.4                                                             127           4.2                                                             128           4.3                                                             129           5.8                                                             130           6.0                                                             131           4.7                                                             132           5.5                                                             133           4.5                                                             134           6.7                                                             135           5.2                                                             136           5.0                                                             137           4.8                                                             138           4.3                                                             139           5.2                                                             140           4.0                                                             141           4.5                                                             142           5.7                                                             143           6.0                                                             144           4.3                                                             145           5.7                                                             146           5.6                                                             147           5.3                                                             148           4.7                                                             149           4.1                                                             150           4.6                                                             151           4.0                                                             152           6.7                                                             153           6.2                                                             154           5.7                                                             155           5.1                                                             156           7.2                                                             157           4.9                                                             158           4.8                                                             159           5.4                                                             160           5.7                                                             161           4.2                                                             162           4.7                                                             163           5.8                                                             164           5.4                                                             165           6.0                                                             ______________________________________                                    

EXAMPLE 25

A photoconductor was produced in the same manner as in Example 1 exceptthat compound No. 171 was used to replace compound No. 1 as a chargegenerating substance.

EXAMPLE 26

A photoconductor was produced in the same manner as in Example 2 exceptthat compound No. 172 was used to replace compound No.2 as a chargegenerating substance.

EXAMPLE 27

A charge transporting layer was formed in substantially the same manneras in Example 26 except that α-phenyl-4'-N,N-dimethylaminostilbene wasused to replace ABPH as a charge transporting substance. Then a chargegenerating layer was formed on the charge transporting layer in the samemanner as in Example 26, thus a photoconductor was produced.

EXAMPLE 28

A charge transporting layer was formed in substantially the same manneras in Example 26 except that tri(p-tolyl)amine was used to replace ABPHas a charge transporting substance. Then a charge generating layer wasformed on the charge transporting layer in the same manner as in Example26, thus a photoconductor was produced.

EXAMPLE 29

A charge transporting layer was formed in substantially the same manneras in Example 26 except that2,5-bis(p-diethylaminophenyl)-1,3,4-oxadia-zole was used to replace ABPHas a charge transporting substance. Then a charge generating layer wasformed on the charge transporting layer in the same manner as in Example26, thus a photoconductor was produced.

The electrophotographic characteristics of the photoconductors thusproduced were measured in the same manner as in Examples 1 to 5 byutilizing an electrostatic recording paper testing apparatus ModelSP-428. The result obtained are shown in Table 9.

                  TABLE 9                                                         ______________________________________                                                 V.sub.s   V.sub.r E.sub.1/2                                                   (volt)    (volt)  (lux · sec)                               ______________________________________                                        Example 25 660         80      5.1                                            Example 26 620         80      5.3                                            Example 27 620         60      5.5                                            Example 28 640         40      4.8                                            Example 29 650         50      4.6                                            ______________________________________                                    

As can be seen in Table 9, the photoconductors of Examples 25 to 29 havegood characteristics in the half decay exposure amounts E_(1/2) and theresidual potentials V_(r).

EXAMPLE 30

100 parts by weight of each of respective bisazo compounds Nos. from 173to 214 and 100 parts by weight of polyester resin (Vylon 200) werekneaded with THF as a solvent with a mixer for 3 hours to prepare acoating liquid. The respective coating liquids were applied ontoaluminum substrates to form a charge generating layer having a drythickness of about 0.5 μm. Further, the coating liquid of ABPH preparedin substantially the same manner as in Example 2 was applied on therespective charge generating layer having a thickness of about 15 μm,thus photoconductors were produced.

The electrophotographic characteristics of the photoconductors thusproduced were measured in the same manner as in Example 6 by utilizingan electrostatic recording paper testing apparatus-SP-428. The resultsof the measurements are shown in Table 10.

As can be seen in Table 10, the photoconductors using the bisazocompound Nos. 173 to 214 as a charge generating substance have goodcharacteristics in the half decay exposure amount E_(1/2).

                  TABLE 10                                                        ______________________________________                                        Compound      E.sub.1/2                                                       No.           (lux · sec)                                            ______________________________________                                        173           4.3                                                             174           4.1                                                             175           4.9                                                             176           5.0                                                             177           5.6                                                             178           5.3                                                             179           5.2                                                             180           6.1                                                             181           5.4                                                             182           4.7                                                             183           5.4                                                             184           6.1                                                             185           5.9                                                             186           5.6                                                             187           5.0                                                             188           5.6                                                             189           5.1                                                             190           4.9                                                             191           5.7                                                             192           4.6                                                             193           4.2                                                             194           5.1                                                             195           6.3                                                             196           4.6                                                             197           4.7                                                             198           3.8                                                             199           5.2                                                             200           3.6                                                             201           5.4                                                             202           5.2                                                             203           4.8                                                             204           5.0                                                             205           4.6                                                             206           4.3                                                             207           6.1                                                             208           5.7                                                             209           5.0                                                             210           5.6                                                             211           4.8                                                             212           4.0                                                             213           4.8                                                             214           4.7                                                             ______________________________________                                    

EXAMPLE 31

A photoconductor was produced in the same manner as in Example 1 exceptthat compound No. 221 was used to replace compound No. 1 as a chargegenerating substance.

EXAMPLE 32

A photoconductor was produced in the same manner as in Example 2 exceptthat compound No. 222 was used to replace compound No. 2 as a chargegenerating. substance.

EXAMPLE 33

A charge transporting layer was formed in substantially the same manneras in Example 32 except that α-phenyl-4'-N,N-dimethylaminostilbene wasused to replace ABPH as a charge transporting substance. Then a chargegenerating layer was formed on the charge transporting layer in the samemanner as in Example 32, thus a photoconductor was produced.

EXAMPLE 34

A charge transporting layer was formed in substantially the same manneras in Example 32 except that tri(P-tolyl)amine was used to replace ABPHas a charge transporting substance. Then a charge generating layer wasformed on the charge transporting layer in the same manner as in Example32, thus a photoconductor was produced.

EXAMPLE 35

A charge transporting layer was formed in substantially the same manneras in Example 32 except that2,5-bis(p-diethylaminophenyl)-1,3,4-oxadiazole was used to replace ABPHas a charge transporting substance. Then a charge generating layer wasformed on the charge transporting layer in the same manner as in Example32, thus a photoconductor was produced.

The electrophotographic characteristics of the photoconductors thusproduced were measured in the same manner as in Examples 1 to 5 byutilizing an electrostatic recording paper testing apparatus ModelSP-428. The result obtained are shown in Table 11.

                  TABLE 11                                                        ______________________________________                                                 V.sub.s   V.sub.r E.sub.1/2                                                   (volt)    (volt)  (lux · sec)                               ______________________________________                                        Example 31 650         60      4.2                                            Example 32 620         70      5.3                                            Example 33 640         50      3.8                                            Example 34 620         30      4.0                                            Example 35 610         30      3.8                                            ______________________________________                                    

As can be seen in Table 11, the photoconductors of Examples 31 to 35have good characteristics in the half decay exposure amounts E_(1/2) andthe residual potentials V_(r).

EXAMPLE 36

100 parts by weight of each of respective bisazo compounds Nos. from 223to 264 and 100 parts by weight of polyester resin (Vylon 200) werekneaded with THF as a solvent with a mixer for 3 hours to prepare acoating liquid. The respective coating liquids were applied ontoaluminum substrates to form a charge generating layer having a drythickness of about 0.5 μm. Further, the coating liquid of ABPH preparedin substantially the same manner as in Example 2 was applied on therespective charge generating layer having a thickness of about 15 μm,thus photoconductors were produced.

The electrophotographic characteristics of the photoconductors thusproduced were measured in the same manner as in Example 6 by utilizingan electrostatic recording paper testing apparatus SP-428. The resultsof the measurements are shown in Table 12.

As can be seen in Table 12, the photoconductors using the bisazocompound Nos. 223 to 264 as a charge generating substance have goodcharacteristics in the half decay exposure amount E_(1/2).

                  TABLE 12                                                        ______________________________________                                        Compound      E.sub.1/2                                                       No.           (lux · sec)                                            ______________________________________                                        223           4.5                                                             224           4.0                                                             225           5.2                                                             226           4.8                                                             227           5.0                                                             228           4.9                                                             229           5.0                                                             230           3.9                                                             231           4.6                                                             232           3.9                                                             233           4.9                                                             234           5.4                                                             235           5.6                                                             236           4.2                                                             237           4.6                                                             238           6.1                                                             239           4.7                                                             240           4.0                                                             241           3.8                                                             242           4.2                                                             243           3.7                                                             244           4.3                                                             245           4.5                                                             246           3.9                                                             247           4.0                                                             248           3.9                                                             249           4.6                                                             250           4.1                                                             251           4.6                                                             252           5.0                                                             253           4.2                                                             254           3.9                                                             255           4.2                                                             256           4.7                                                             257           5.6                                                             258           5.1                                                             259           3.7                                                             260           5.0                                                             261           4.7                                                             262           4.6                                                             263           4.2                                                             264           4.5                                                             ______________________________________                                    

EXAMPLE 37

A photoconductor was produced in the same manner as in Example 1 exceptthat compound No. 271 was used to replace compound No. 1 as a chargegenerating substance.

EXAMPLE 38

A photoconductor was produced in the same manner as in Example 2 exceptthat compound No. 272 was used to replace compound No. 2 as a chargegenerating substance.

EXAMPLE 39

A charge transporting layer was formed in substantially the same manneras in Example 38 except that α-phenyl-4'-N,N-dimethylaminostilbene wasused to replace ABPH as a charge transporting substance. Then a chargegenerating layer was formed on the charge transporting layer in the samemanner as in Example 38, thus a photoconductor was produced.

EXAMPLE 40

A charge transporting layer was formed in substantially the same manneras in Example 38 except that tri(p-tolyl)amine was used to replace ABPHas a charge transporting substance. Then a charge generating layer wasformed on the charge transporting layer in the same manner as in Example38, thus a photoconductor was produced.

EXAMPLE 41

A charge transporting layer was formed in substantially the same manneras in Example 38 except that2,5-bis(p-diethylaminophenyl)-1,3,4-oxadiazole was used to replace ABPHas a charge transporting substance. Then a charge generating layer wasformed on the charge transporting layer in the same manner as in Example38, thus a photoconductor was produced.

The electrophotographic characteristics of the photoconductors thusproduced were measured in the same manner as in Examples 1 to 5 byutilizing an electrostatic recording paper testing apparatus ModelSP-428. The result obtained are shown in Table 13.

                  TABLE 13                                                        ______________________________________                                                 V.sub.s   V.sub.r E.sub.1/2                                                   (volt)    (volt)  (lux · sec)                               ______________________________________                                        Example 37 660         20      4.9                                            Example 38 630         50      5.1                                            Example 39 620         80      5.3                                            Example 40 630         60      4.1                                            Example 41 650         50      4.3                                            ______________________________________                                    

As can be seen in Table 13, the photoconductors of Examples 37 to 41have good characteristics in the half decay exposure amounts E_(1/2) andthe residual potentials V_(r).

EXAMPLE 42

100 parts by weight of each of respective bisazo compounds Nos. from 273to 314 and 100 parts by weight of polyester resin (Vylon 200) werekneaded with THF as a solvent with a mixer for 3 hours to prepare acoating liquid. The respective coating liquids were applied ontoaluminum substrates to form a charge generating layer having a drythickness of about 0.5 μm. Further, the coating liquid of ABPH preparedin substantially the same manner as in Example 2 was applied on therespective charge generating layer having a thickness of about 15 μm,thus photoconductors were produced.

The electrophotographic characteristics of the photoconductors thusproduced were measured in the same manner as in Example 6 by utilizingan electrostatic recording paper testing apparatus SP-428. The resultsof the measurements are shower in Table 14.

As can be seen in Table 14, the photoconductors using the bisazocompound Nos. 273 to 314 as a charge generating substance have goodcharacteristics in the half decay exposure amount E_(1/2).

                  TABLE 14                                                        ______________________________________                                        Compound      E.sub.1/2                                                       No.           (lux · sec)                                            ______________________________________                                        273           5.2                                                             274           3.8                                                             275           4.6                                                             276           5.3                                                             277           6.1                                                             278           4.7                                                             279           4.4                                                             280           4.9                                                             281           5.4                                                             282           5.9                                                             283           5.5                                                             284           4.7                                                             285           6.3                                                             286           4.1                                                             287           4.0                                                             288           3.8                                                             289           4.7                                                             290           4.4                                                             291           5.3                                                             292           4.2                                                             293           5.8                                                             294           6.7                                                             295           4.9                                                             296           5.5                                                             297           4.7                                                             298           4.4                                                             299           4.9                                                             300           3.6                                                             301           4.5                                                             302           4.7                                                             303           6.1                                                             304           5.8                                                             305           4.8                                                             306           4.0                                                             307           5.1                                                             308           5.7                                                             309           5.5                                                             310           5.6                                                             311           4.7                                                             312           4.1                                                             313           4.0                                                             314           4.2                                                             ______________________________________                                    

EXAMPLE 43

A photoconductor was produced in the same manner as in Example 1 exceptthat compound No. 321 was used to replace compound No. 1 as a chargegene-rating substance.

EXAMPLE 44

A photoconductor was produced in the same manner as in Example 2 exceptthat compound No. 322 was used to replace compound No. 2 as a chargegenerating substance.

EXAMPLE 45

A charge transporting layer was formed in substantially the same manneras in Example 44 except that α-phenyl-4'-N,N-dimethylaminostilbene wasused to replace ABPH as a charge transporting substance. Then a chargegenerating layer was formed on the charge transporting layer in the samemanner as in Example 44, thus a photoconductor was produced.

EXAMPLE 46

A charge transporting layer was formed in substantially the same manneras in Example 44 except that tri(p-tolyl)amine was used to replace ABPHas a charge transporting substance. Then a charge generating layer wasformed on the charge transporting layer in the same manner as in Example44, thus a photoconductor was produced.

EXAMPLE 47

A charge transporting layer was formed in substantially the same manneras in Example 44 except that2,5-bis(p-diethylaminophenyl)-1,3,4-oxadiahole was used to replace ABPHas a charge transporting substance. Then a charge generating layer wasformed on the charge transporting layer in the same manner as in Example44, thus a photoconductor was produced.

The electrophotographic characteristics of the photoconductors thusproduced were measured in the same manner as in Examples 1 to 5 byutilizing an electrostatic recording paper testing apparatus ModelSP-428. The result obtained are shown in Table 15.

                  TABLE 15                                                        ______________________________________                                                 V.sub.s   V.sub.r E.sub.1/2                                                   (volt)    (volt)  (lux · sec)                               ______________________________________                                        Example 43 620         50      4.3                                            Example 44 590         20      4.8                                            Example 45 660         60      5.1                                            Example 46 630         60      5.3                                            Example 47 600         40      4.7                                            ______________________________________                                    

As can be seen in Table 15, the photoconductors of Examples 43 to 47have good characteristics in the half decay exposure amounts E_(1/2) andthe residual potentials V_(r).

EXAMPLE 48

100 parts by weight of each of respective bisazo compounds Nos. from 323to 386 and 100 parts by weight of polyester resin (Vylon 200) werekneaded with THF as a solvent with a mixer for 3 hours to prepare acoating liquid. The respective coating liquids were applied ontoaluminum substrates to form a charge generating layer having a drythickness of about 0.5 μm. Further, the coating liquid of ABPH preparedin substantially the same manner as in Example 2 was applied on therespective charge generating layer having a thickness of about 15 μm,thus photoconductors were produced.

The electrophotographic characteristics of the photoconductors thusproduced were measured in the same manner as in Example 6 by utilizingan electrostatic recording paper testing apparatus SP-28. The results ofthe measurements are shown in Table 16.

As can be seen in Table 16, the photoconductors using the bisazocompound Nos. 323 to 386 as a charge generating substance have goodcharacteristics in the half decay exposure amount E_(1/2).

                  TABLE 16                                                        ______________________________________                                        Compound      E.sub.1/2                                                       No.           (lux · sec)                                            ______________________________________                                        323           4.0                                                             324           4.9                                                             325           4.7                                                             326           4.0                                                             327           4.4                                                             328           4.8                                                             329           5.3                                                             330           6.1                                                             331           5.8                                                             332           4.3                                                             333           5.2                                                             334           4.5                                                             335           5.1                                                             336           5.3                                                             337           6.2                                                             338           4.8                                                             339           5.3                                                             340           4.7                                                             341           4.3                                                             342           6.0                                                             343           6.2                                                             344           5.5                                                             345           4.6                                                             346           4.7                                                             347           5.6                                                             348           4.5                                                             349           4.2                                                             350           4.7                                                             351           5.1                                                             352           5.2                                                             ______________________________________                                    

                  TABLE 8                                                         ______________________________________                                        Compound      E.sub.1/2                                                       No.           (lux · sec)                                            ______________________________________                                        353           4.7                                                             354           4.6                                                             355           4.7                                                             356           6.0                                                             357           5.8                                                             358           4.1                                                             359           3.7                                                             360           4.0                                                             361           4.9                                                             362           6.9                                                             363           4.7                                                             364           4.1                                                             365           5.8                                                             366           4.7                                                             367           5.2                                                             368           5.7                                                             369           4.2                                                             370           4.9                                                             371           5.8                                                             372           4.4                                                             373           5.1                                                             374           5.9                                                             375           4.6                                                             376           4.7                                                             377           3.5                                                             378           5.9                                                             379           6.0                                                             380           4.8                                                             381           4.1                                                             382           6.4                                                             383           5.8                                                             384           4.4                                                             385           4.8                                                             386           4.6                                                             ______________________________________                                    

As described above, according to the present invention, since a bisazocompound represented by any one of the aforementioned chemical formulaeis used as a charge generating substance in a photosensitive layerformed on an electroconductive substrate, a photoconductor shows a highsensitive and excellent characteristics in repeated use when adapted toeither a positive charge mode or a negative charge mode. If necessary, acovering layer may be provided on the surface of a photoconductor toimprove the durability thereof.

The invention has been described in detail with respect to preferredembodiments, and it will now be apparent from the foregoing to thoseskilled in the art that changes and modifications may be made withoutdeparting from the invention in its broader aspects, and it is theinvention, therefore, in the appended claims to cover all such changesand modifications as fall within the true spirit of the invention.

What is claimed is:
 1. A photoconductor for electrophotography,comprising:an electroconductive substrate; and a photosensitive layerformed on said electroconductive substrate and including a chargetransporting substance and a charge generating substance which is atleast one bisazo compound represented by general formula (VI):##STR413## wherein each of R₉ and R₁₀ is selected from the groupconsisting of a hydrogen atom, a halogen atom, an alkyl group and anaryl group, and A₁ is a coupler residual group represented by one ofgeneral formulae (IX) to (XV): ##STR414## wherein Z is a residual groupwhich condenses with a benzene ring to form an aromatic polycycle orheterocycle, X₁ is one of OR₁ and NR₂ R₃, each of R₁, R₂ and R₃ isselected from the group consisting of a hydrogen atom, an alkyl group,an aryl group and a heterocyclic group, which groups may be each of X₂and X₅ is selected from the group consisting of an alkyl group, an arylgroup and a heterocyclic group, which groups may be substituted, each ofX₃ and X₆ is selected from the group consisting of a hydrogen atom, acyano group, a carbamoyl group, a carboxyl group, an ester group and anacyl group, each of X₄ and X₁₁ is selected from the group consisting ofa hydrogen atom, an alkyl group, a cycloalkyl group, an alkenyl group,an aralkyl group, an aryl group and a heterocyclic group, each of X₇ andX₈ is selected from the group consisting of a hydrogen atom, a halogenatom, a nitro group, an alkyl group and an alkoxy group the alkyl groupand the alkoxy group of which may be substituted, X₉ is selected fromthe group consisting of an alkyl group, an aryl group, a carboxyl groupand an ester group, X₁₀ is one of an aryl group and a heterocyclicgroup, which groups may be substituted, and Y is a residual group whichforms an aromatic ring or a heterocycle.
 2. The photoconductor asclaimed in claim 1, wherein said photosensitive layer comprises a layerincluding a binder in which is dispersed the charge generating substanceand the charge transporting substance.
 3. The photoconductor as claimedin claim 1, wherein said photosensitive layer comprises a laminate of acharge transporting layer mainly composed of the charge transportingsubstance and a binder, and a charge generating layer including thecharge generating substance and a binder.